BPM problems

ez peeps. just noticed this recently. i use traktor to dj on a laptop, and i noticed that whenever one of my own tracks is loaded up, it never says 174 bpm or whatever it is, but half that bpm. for xample, if it was 174 bpm, itd show up as 87 bpm. anyone know what could be the problem? it happens with other artist's tracks sometimes too.